Some of these are difficult, so challenge yourself!
"Pre-School" Test for you:
Which way is the bus below traveling...toward the left or the right?
Can't make up your mind? Look carefully at the picture again. Pre-schoolers all over the United States were shown this picture and asked the same question, and 90% of them gave the correct answer!
You must cut a gold chain to pay someone for 7 days of service. The chain has 7 links on it, and you agree on a price of one link per day. The employee will not work without receiving that day's pay each afternoon, but you do not wish to give him more than his daily payment for the fear that he will not return. Therefore, you must cut some of the links on the chain to make the daily payments. What is the smallest number of links you need to cut so that the employee receives only one link each day?
While driving home after a hard day's work, I came upon the following problem. An entire town had been painted black; the roads, pavements, buildings, hedges, and everything that did not move had been painted black. In addition, my vehicle's headlights were not working, no moon was visible, and power was off in the area, so there were no street or house lights around. At that moment, I entered a curve where a solid black dog (deaf, and thus unaware of the approaching car) was sitting in the road. He had his back to me, so there was not even a glint in his eye, yet I was able to swerve round him quite easily and without danger. How was this achieved?
A man has an acreage where grass grows continuously and evenly. If 20
cows eat all the grass in 96 days and 30 cows eat all of the grass in 60
days, then how long does it take 70 cows to eat all of the grass?
You have three houses or squares drawn on paper, and below them three smaller squares representing gas, water, and electric service. Can you draw a line to get each utility into each house (9 total lines) without crossing over any line, changing the size of some of the houses, or going through one house to reach another?
Good at math? Try this one....
1=3
2=3
3=5
4=4
5=4
6=3
7=5
8=5
9=4
10=3
So what does
11=?
12=?
What do these words have in common: age, blame, curb, dance, evidence, fence, gleam, harm, interest, jam, kiss, latch, motion, nest, order, part, quiz, rest, signal, trust, use, view, win, x-ray, yield, zone?
What are the science teacher's favorite states?
You have three containers. One has only red marbles, one has only blue marbles and the third has an equal number of red and blue marbles. The labels on the containers have intentionally been switched so that each container is now marked incorrectly.
Your job is to relabel the containers correctly. Of course you could just look in the containers to find out which labels match, but can you do it without looking into each container? Reach into any one of the containers and select one marble. Can you now correctly label all three containers? If not, select a second marble from any container. What is the fewest number of marbles you need to inspect in order to correctly label each container?
During a school lunch break, ten kids are discussing after school jobs. In particular, they would like to know their average monthly salary (for the ten of them), but no one wants to admit openly exactly what they make. Can you devise a way for them to calculate their average (mean) salary without anyone having to tell anyone else what their individual salaries are?
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More detailed explanation for the Postman Riddle:
The most important feature to recognize in solving this puzzle is that Postman A needed to know that Postman B did not have twins in order to solve the puzzle. That means that there must be two possible solutions that satisfied the "age in years" and "number of windows" conditions of the problem. He needed to rule out twins to solve the problem. To summarize, there must have been two potential solutions with 3 son's ages having:
(i) equal products (the age condition)
(ii) equal sums (the windows condition)
(iii) one involving twins and one not.
If you really wanted to be fussy, since a house cannot have a fraction of a window, it also means that the ages of the sons must all be in integers (whole numbers) and not involve fractional ages.
The one solution to the problem that satisfies all of these conditions is (1, 5, 8) which has the same sum (14) and the same product (40) as another possible solution involving twins (2, 2, 10). There is just no other solution that works involving a postman's age less than 90 years old. That is, another solution that works mathematically is 2-5-9 and 3-3-10, but that would make the postman 90 years old.
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